Grinding-mill.



J. K. GRIFFITH.

GRINDING MILL.

APPLICATION FILED APR. 18. 1915.

Patented Feb. 25, 1919.

4 SHEETS-SHEET I.

WITNESSES J. K. GRIFFITH.

GRINDING MILL.

APPLICATION FILED APR. 18 I916.

Patentsfl Feb. 25 191%..-

I; J! 1; I

- J. K. GRlFFHH.

amma MILL.

W APPLICATION FILED APR. TS, 1916. IL QAQQ Patented Feb. 20, 1919.

4 SHEETSSHEET 3.

III/III III/III WIE'NEQaSEES 4 INVENTOR J. K. GRIFFITH.

GRINDING MILL.

APPLlCA-HON FILED APR. *8. i916.

1 295A2a Patsntefi Feb 25, 1919.

'4 SHEETS-SHEEF 4.

WITNESSES J'AUOB K. GRIFFITH, OF PITTSTON', PENNSYLVANIA, ASSIGNOR TO A. J'. GRIFFITH, F

-IEITTSTON, PENNSYLVANIA. 4

GRINDING-MILL.

Specification of Letters Patent.

V To all whom it may concern:

. c Be it known that I, JACOB K. Giirrrrrn, a

citizen of the United States, residing at Pitts ton, in the county of Luzerne and State of Pennsylvania, have invented a new and useful Improvement in Grinding-Mills, of which the following is a full, clear, and exact description, reference being had: to the accompanying drawings, forming part of this specification, in which:

Figures 1, 2, 3, 1 and 5 are diagrams illustrating positions which may be assumed by one "form of grinding'units embodying my invention.

I Figs. 6 and 7 are sectional views taken in planes at right angles to each other, illustrating another form of my invention.

Fig. 8 is a cross sectional View of the tube mill showing another form of the invention. Fig. 9 is a sectional view on the line IX-IX of Fig. 8.

Fig. 10 is a View partly in side elevation and partly in section of one of the units shown in Figs. Stand 9.

Figs. 11, 12 and 13 are diagrams illustrating the advantages of my invention.

Figs. 14 and 1b are comparative diagrams further illustrating such advantages.

My invention has relation to improvements in mills for the grinding of cement,

or ores of the precious metals for concen tration, flotation, cyanj iation and amalgamation; or to other grinding mills in which it .is desirable to grind'the material finer and at less cost than in the mills at present used.

For many years the fine grinding of cement clinkers has been largely carried out by the use of so called tube mills, in which quartz pebbles were used as grinding elementsv More recently these quartz or flint pebbles have been replaced to a large extent by the use of steel slugs and balls. By the use of balls of 1" diameter the output has been increased about 25 per cent. due to the increase in the points of contact as well as to the increase in the weight of the balls over that of pebbles. By the use of slugs (which are chilled iron or steel cylinders of about one inch in diameter by one and onehalf inches long) a still larger area of grinding surface is obtained, this enabling the over that with flint pebbles. ball-mills for grindingore has been adopted Patented Feb. 25, 1919..

output to be increased about 40 per cent.

The use of from the cement industry.

My invention is designed to provide grinding units or elements in which the area of contact, as well as the efficiency of action due to increased weight and other causes, is so arranged that the resulting output of the mill is very greatly increased.

To this end, my invention consists in thewhat may be termed double or twin balls.

That is to say, each element consists of two hall-shaped end portion-s2, connected byan intermedlate portion 3 of reduced diameter.

The weight and size of these units can be fixed at Wlll- In use. they may be placed in any type of mill of this general class, and the mill operated in the same manner as with the pebbles, balls or slugs'at present in use.

The advantages of this form of my invention as compared with the original ball elements will be more apparent by a comparison of Figs. 14: and 15. When balls are employed, such as. illustrated in Fig. 15, assuming that a ball is 1 in diameter and is surrounded by other balls of the same size, it will require 12 balls to surround it on all sides, and as these balls only touch the center ball at 12 points, the complete group will have 14 interstices.

In accordance with my invention, the 18 balls shown in Fig. 15 would be replaced by 9 of the twin balls shown in Fig. 14, giving only 8 interstices compared with 20 interstices shown in Fig. 15, or 60 per cent. less.

The greater area of contact between the elements obtained by my invention will also be apparent from Figs. 11, i2 and 13.

In Fig. 11, I have shown double balls such as would be formed by uniting two balls which would touch each other if not united.

In this case the arc of contact is 60 of a circle, or .785" long with a ball of 19 in diameter. When the double balls touch each. other longitudinally, the line of contact is 1.57" in length Fig. 12 shows double balls formed b uniting two single balls, which if not unite would be i apart. form, the arc of contact is 7 2, or .94" in length and when assembled longitudinally, the line of contact is 1.88 in length.

ce'pt that the two balls if notunited would of contact 85, or to 1.15? inlength and increases the longitudinal line ofcontact to 2.3"; in length. This line of contactis 73 longer or 32 per cent. more than that shown .in' Fig. 11. The -arrangement-',shown in Fig. 11 gives anfe'fliciency ofl about per cent. greater than that-ofc -s ngle balls and the efiiciencyv of the arrangement shown in Fig. 13 is about 92 per ,centl greater than that resulting from the use of single balls.

A further advantage of my invention results from the fact that when the double balls are assembled they are in such relation to each other that they cannot be easily separated while under pressure. The material being ground is, therefore, confined much more closely and is ground much more finely than with the usual pebbles, balls or slugs. Furthermore, inasmuch as the circumference of the end portions 2 of the balls is considerably greater than the circumference of the central portion 3, when the balls are in contact and revolving, the end portions have a very much greater surface velocity than that of the central portions. This produces a disintegrating action which is somewhat similar in its nature to the grinding efi'ect produced by the old fashioned mill stones. This is an important feature which greatly increases the grinding efficiency. A still further unique feature of the invention is that the more the units become-worn, the greater is their efiiciency, since wear results in increasing their contact areas.

In use, the elements or units may assume an almost kaleidoscopic number of difi'erent positions, some of which I have illustrated in Figs. 1 to 5. These, of course, are illustrative only.

Instead of employing double ball units or elements, I may employ elements having three or more lobes or ball portions; and in fact the elements may take the form of loose rolls, as shown in Figs. 6 to 10, inclusive.

6 and 8. With this form, I prefer to corportions of the grinding elements. If de sired, the" lining of the mill may also be cor- I 'rugatedlongitudinally, shown at- 8 in Fig. 13 shows a similararrangement -ex-'wFigI.l8.--"

stead or, making the'units in a number be separated by g". This increases the arc of separate section'sy'as shown in Fig. 7 ,they may be cast of the "desired length, in a single piece, as shown at 9 in'Figs. 8, 9 and 10. g 1 Y a By the use of these elements, the grinding is produced not only by their weight and revolving action, but by the V-shaped ball '80 portions of one element forcing their way in the grooves of the same sha in the adjacent elements and in the lining plates of. the mill. In short tube mills, these grinding elements could be made very heavy so i With elements of relatively large diameter,

this proportion of difierence can be increased. I

The elements may be made of any metal best suited to the work they are to be used for, such as chilled cast iron, high carbon steel, oil tempered, or any suitable alloy steel. They may be either rolled or cast.

The advantages of my invention in improving the etficiency of this class of mills will be readily apparent to those skilled in this art.

I claim:

1. The combination with a comminuting mill of a plurality of grinding bodies therein free to move in any direction with relation to each other and of a general dumb-bell shape having rounded or convex end'portions and a reduced rounded neck portion connecting the convex end portions, and forming a saddle-shaped surface which is adapted for co-action with the convex surface of the end portion of another body, substantially as described '2. The combination with a comminuting mill, of a plurality of tumbling grinding bodies therein, free to move in any direction surfacehaving a reentrant curvature approximately equal to the curvature of the I end portions, so that the neck portion of one -.body is adapted ,to conform to and coact" with the end portion of another'hody.

' mill having ageneral dumb-bell shape, hav.--

3'. A grinding body for use in a tumbling ing rounded or convert end portions 'and a reduced rounded neck portion connecting the end portions" and having .a rentrant curvature of substantially the same radius as thecurvature of the end portions and 'adaptedto co act with the end portion .of antilt other and similar body so as to have continuous surface contact therewith, substantially as described.

4. The combination-with a eomminuting millof a tumbling grinding body, free to move in any direction therein and of a gen:

eral dumb bell shape, having rounded or convex end portions and a reduced rounded neck portion connecting the convex end por-. tions, and/a second tumbling grinding body also free to move in any direction therein and of a general dumb-bell shape having 7 rounded or convex end portions and 'a reduced rounded neck portion connecting the convex end portions, the neck portion of one bodyf being adapted to conform to and co-act with the end portion of the other body, substantially as described.

5. A tube mill having marlin circurnferential corrugations and a plurality of loose grinding elements having enlarged portions and intermediate connecting portions of less diameter and of a surface contour fitting the corrugations of the mill I and fitting the other grinding elements, substantially as described. 4

. 6. A tube mill having internal circumferential corrugations, a plurality of loose grindi elements. having approximately spherica portions and intermediate connect ing portions of less diameter than, the

lspheric'al portions and of a surface contour fitting the corrugations of the mill and fitting the other grinding tially as described.

elements, substan- 'necting the convex end portions and forming a saddle-shaped surface which is adapted for coaction with the convex end surfaces of other similar u'nits, substantially as described In testimony whereof, I have hereunto set my hand.

JACOB K. GRIFFITH.

Witnesses:

WINIFRED GRIFFITH, J. R. EHRET. 

